This invention relates to a panel, particularly a flooring panel, which can be mechanically interlocked with other identical panels.
These types of panels are commonly used for floor coverings, such as, for example, parquet or laminate floor coverings. These types of panels can also be used to cover other surfaces such as ceilings and walls. Often, wooden materials are used to fabricate such panels, particularly, for example, particle board, MDF (medium density fiberboard) boards and HDF (high density fiberboard) boards. Alternatively, plastics can be used.
Individual panels are installed by mechanically joining (i.e., interlocking) them into a flat whole. Preferably, the panels are laid without adhesive or additional mechanical fasteners (e.g., screws or nails). This advantageously allows them to be more easily replaced or removed without damage.
A known panel has a tongue-and-groove joint for locking interconnected panels in the vertical direction. A metal strip mounted on and extending outward from the bottom of one panel engages a corresponding groove in the bottom of another panel for locking the interconnected panels in the horizontal direction. A xe2x80x9cvertical lockxe2x80x9d limits or prevents interlocked panels from moving relative to each other in the vertical direction, while a xe2x80x9chorizontal lockxe2x80x9d limits or prevents interlocked panels from moving relative to each other in the horizontal direction. The bottom of the groove and the top of the tongue are usually aligned substantially parallel to the top of the panel such that a preferably exact vertical fit of interconnected panels is achieved (i.e., the top surfaces of the interconnected panels lie in the same plane).
Improvements to this panel are also known (see, e.g., WO 01/66876 and WO 01/48331). In such improved panels, a tongue-and-groove joint provides the vertical lock and a locking-lip-and-tongue joint provides the horizontal lock. Both sets of locking structures are preferably formed integrally with the panel. The locking lip is implemented on the same side edge as the tongue and the locking tongue is implemented on the same side edge as the groove. In many such panels, the locking tongue also simultaneously serves as the lower lip of the groove, thus playing a role-in both vertical and horizontal locking of interconnected panels.
The locking lip is typically the only structure that is elastically deformed (usually downward) during the interconnection of two panels. This downward deformation allows the locking lip to fully engage the locking tongue. However, because the top of the locking tongue abuts the bottom of the tongue-and-groove tongue, the locking tongue typically cannot bend upward, providing no relief to the interconnection force applied to the locking lip. In some cases, this may cause the locking lip to bend too far downward, which can damage the panel by causing fine cracks in the region of the locking lip. This can weaken and perhaps ruin the panel interconnection.
In view of the foregoing, it would be desirable to be able to provide a panel having integrally formed vertical and horizontal locking structures that are not likely to be damaged when such panels are interconnected.
It is an object of this invention to provide a panel having integrally formed vertical and horizontal locking structures that are not likely to be damaged when such panels are interconnected.
A panel constructed in accordance with the invention has first and second side edges preferably opposite each other. The first side edge can be interlocked with the second side edge of another panel of the invention. The side edges have upper lateral faces running substantially perpendicular to the top of the panel. The first side edge has a groove extending parallel to the first side edge delimited by an upper lip and a lower lip. The second side edge has a tongue extending parallel to the second side edge. The first and second side edges interlock such that the upper lateral faces abut one another and the tongue fits in the groove (i.e., the top of the tongue abuts the bottom of the upper lip, and the bottom of the tongue abuts the top of the lower lip).
The first side edge further includes a locking lip at a distance from the lower lip. The locking-lip has a locking face running at a slant with respect to the bottom of the panel. Preferably, the locking face is an inclined surface. The inclined surface preferably has a positive slope (i.e., the surface extends upward toward the second side edge of another panel).
The second side edge further includes a locking tongue at a distance from the first tongue. The locking tongue has a locking face running at a slant with respect to the bottom of the panel. As above, the locking face is preferably an inclined surface preferably having a positive slope.
A panel constructed according to the invention thus has a locking tongue on the same side edge as the tongue of the tongue-and-groove joint and has a locking lip on the same side edge (preferably opposite the other side edge) as the groove of the tongue-and-groove joint. The first side edge of one panel interlocks the second side edge of another panel such that the locking face of the locking lip butts against the locking face of the locking tongue.
Advantageously, in the locked state, an interval (i.e., a space) is provided between the bottom of the lower lip and the top of the locking tongue. This interval advantageously allows the locking tongue to deform elastically upward during joining, preferably resulting in the locking lip deforming less downward. This reduces, if not prevents, the likelihood of damage to the locking structures. In addition, the interval allows relative movement of both the tongue-and-groove joint and the locking-lip-and-tongue joint should mechanical stress (e.g., a person standing) near the interlocked side edges occur. This further avoids damage to the locking structures.
The size of the interval need only be large enough to prevent a xe2x80x9cfitxe2x80x9d between the bottom of the lower lip and the top of the locking tongue. That is, the interval should be large enough to prevent the bottom of the lower lip from abutting the top of the locking tongue. If a fit did occur (i.e., those surfaces were in contact with each other), a double fit would exist between that and the tongue-and-groove joint. This would be technically difficult to implement reliably because of production tolerances. The interval should therefore be greater than about 0.05 mm, preferably greater than about 0.1 mm, and more preferably greater than about 0.5 mm.
Preferably, another interval (i.e., another space) is also provided in the locked state between the distal end surface of the locking tongue and the back surface or base of the groove or depression formed by the lower lip and the locking lip. This interval supplements the interval described above. Preferably, only the bottom of the locking tongue abuts the locking lip.
In sum, the locking structures are integrally formed as part of a one-piece panel in which the vertical and horizontal locking structures of the panel are advantageously completely separate and distinct from each other. They are separate and distinct because the tongue and groove form no part of the locking lip and locking tongue and vice versa.
Panels of the invention preferably also include an additional step or plane in the side edge profile to additionally protect against the penetration of moisture.
Some embodiments of the invention preferably have the distal end of the locking tongue extending beyond the distal end of the tongue-and-groove tongue. This is likely to result in delivery of the impact or interconnection force solely by the distal end of the locking tongue during the joining of the panels. This protects all other projecting structures of both side edges. In particular, the upper lateral face of the first panel, which forms a part of the aesthetically important visible joint edge between both panels, and the elements of the tongue-and-groove joint, are advantageously not subjected to the applied impact force and thus remain undeformed.
In another embodiment of the invention, a projecting rib or protrusion is provided at the lower end of the upper lateral face of the first side edge, and a corresponding depression or indentation sized to receive the protrusion is provided at the lower end of the upper lateral face of the second side edge. The protrusion engages the indentation in the locked state. This engagement defines the exact position of the forward end of the upper lip, through which displacement of the upper lip caused by stress of the panels near the side edges or by penetration of moisture is reduced if not prevented. Note that the protrusion and indentation feature is independent of the other embodiments and may be used in other tongue-and-groove joints with or without mechanical locking.
In a further embodiment of the invention, the base of the depression delimited between the lower lip and the locking lip projects beyond a plane substantially perpendicular to the top of the panel and substantially aligned with the upper lateral face of the first side edge. In other words, the back surface of a second groove formed by the lower lip of the first groove (of the tongue-and-groove joint) and the locking lip is located beyond (i.e., further outward or forward on the first side edge than) the plane substantially aligned with the upper lateral face of the first side edge.
This embodiment has the advantage of not transmitting forces received by the panels near the side edges directly downward onto the horizontal locking structures. In particular, a solid region (i.e., a region with no grooves or depressions) is positioned directly below the side edges, so that applied forces (from, e.g., a table or chair leg) do not lead directly to deformation of the elastic elements of the horizontal lock, which are positioned beyond the upper lateral face of the first side edge. Another advantage is that the bottom of the tongue and the top of the lower lip are greatly lengthened and form an expanded contact surface.
Finally, in still another embodiment of the invention, the forward end of the locking tongue has an enlarged outer shape, which in the locked state, fits or butts against the bottom of the lower lip in the second groove formed by the lower lip and the locking lip. An interval still exists between the remaining top portion of the locking tongue (i.e., the non-enlarged portion) and the lower lip and thus the freedom of movement of the locking tongue is not restricted. The fit at the distal (i.e., forward) end of the locking tongue results in a more stable horizontal lock. Advantageously, the tongue-and-groove joint is not adversely affected by this, because the horizontal extent of the fit of the tongue-and-groove joint inside the profile of the edges does not vertically overlap the horizontal extent of the fit at the distal end of the locking tongue. A double fit therefore does not occur in this region.
In sum, panels of the invention ensure that the locking structures which are expected to deform as a result of the joining of panels can do so without being damaged and without impairing the fit of other locking structures whose precise shape is needed for the exact fit of one panel with another. Advantageously, this reliable joining of panels is achieved by having completely separate vertical and horizontal locking structures, with an interval between the locking tongue and the lower lip.